Response

Indeed you are correct that the elevated TH levels and non-suppressed TSH are consistent with Resistance to Thyroid Hormone. RTH TSH secreting pituitary tumor antibodies interfering with measurement of the thyroid hormone levels or TSH. Transient elevations in the TH levels are also seen following certain viral syndromes. Is there any family history of thyroid abnormalities? : -Measurement of the alpha subunit (elevated alpha SU:TSH ratios are seen in the TSHomas) -Measurement of antithyroid antibodies, if negative would make interfering substances less likely -Determination of thyroid hormone function in parents, children, siblings (where possible). If there are other affected individuals it makes the diagnosis of RTH more likely -Obtain an MRI of the pituitary -Measure SHBG in serum (if elevated it would be consistent with a TSHoma) -Send blood for DNA analysis of Thyroid Hormone Receptor beta mutation to Quest Diagnostics The presence of decreased BMD is commonly seen in generalized RTH (GRTH). The reason being that the primary thyroid hormone receptor in bone is the TR alpha. Since it is the TR beta gene which is abnormal in most patients with GRTH, the TR alpha gene is normal and responds to the high thyroid hormone levels dictated by the pituitary. Hence the bone loss. The colloid nodule is likely incidental, as there is no evidence of increase thyroid nodules or thyroid cancer in RTH. Before recommending a specific treatment, it would be best to have a definitive diagnosis which explain the thyroid tests. My recommendations above should help sort this out. Please let me know the results of the testing and if you have any further questions, please feel free to contact me directly.